Analytical Model for the Destruction Mechanism of GTO-Like Devices by Avalanche Injection

The turn-off capability of power devices based on the gate turn-off (GTO) principle is basically limited by avalanche injection. This fundamental phenomenon causes the device to run into a critical state where both voltage and current are pinned at a high level and, moreover, the current is inhomogeneously carried by filaments which freely travel around the device, until ultimately thermal destruction occurs. For this mechanism, an analytical model has been developed from very basic principles, which couples charge carrier transport via drift and diffusion with thermal conduction. It gives insight into the details of the failure and destruction mechanism and, among others, is useful for estimating the safe operating area (SOA) of GTO-like devices.